From fb9a16a1a6f24f5bbf05ca7a49bd4305575cc2f2 Mon Sep 17 00:00:00 2001 From: Thomas Munro Date: Sun, 22 Oct 2023 10:04:55 +1300 Subject: [PATCH] Fix min_dynamic_shared_memory on Windows. When min_dynamic_shared_memory is set above 0, we try to find space in a pre-allocated region of the main shared memory area instead of calling dsm_impl_XXX() routines to allocate more. The dsm_pin_segment() and dsm_unpin_segment() routines had a bug: they called dsm_impl_XXX() routines even for main region segments. Nobody noticed before now because those routines do nothing on Unix, but on Windows they'd fail while attempting to duplicate an invalid Windows HANDLE. Add the missing gating. Back-patch to 14, where commit 84b1c63a added this feature. Fixes pgsql-bugs bug #18165. Reported-by: Maxime Boyer Tested-by: Alexander Lakhin Discussion: https://postgr.es/m/18165-bf4f525cea6e51de%40postgresql.org --- src/backend/storage/ipc/dsm.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/src/backend/storage/ipc/dsm.c b/src/backend/storage/ipc/dsm.c index b461a5f7e96..83ca9595e8e 100644 --- a/src/backend/storage/ipc/dsm.c +++ b/src/backend/storage/ipc/dsm.c @@ -920,7 +920,7 @@ dsm_unpin_mapping(dsm_segment *seg) void dsm_pin_segment(dsm_segment *seg) { - void *handle; + void *handle = NULL; /* * Bump reference count for this segment in shared memory. This will @@ -931,7 +931,8 @@ dsm_pin_segment(dsm_segment *seg) LWLockAcquire(DynamicSharedMemoryControlLock, LW_EXCLUSIVE); if (dsm_control->item[seg->control_slot].pinned) elog(ERROR, "cannot pin a segment that is already pinned"); - dsm_impl_pin_segment(seg->handle, seg->impl_private, &handle); + if (!is_main_region_dsm_handle(seg->handle)) + dsm_impl_pin_segment(seg->handle, seg->impl_private, &handle); dsm_control->item[seg->control_slot].pinned = true; dsm_control->item[seg->control_slot].refcnt++; dsm_control->item[seg->control_slot].impl_private_pm_handle = handle; @@ -988,8 +989,9 @@ dsm_unpin_segment(dsm_handle handle) * releasing the lock, because impl_private_pm_handle may get modified by * dsm_impl_unpin_segment. */ - dsm_impl_unpin_segment(handle, - &dsm_control->item[control_slot].impl_private_pm_handle); + if (!is_main_region_dsm_handle(handle)) + dsm_impl_unpin_segment(handle, + &dsm_control->item[control_slot].impl_private_pm_handle); /* Note that 1 means no references (0 means unused slot). */ if (--dsm_control->item[control_slot].refcnt == 1)